In modern lightwave telecommunication systems such as wavelength-division-multiplexed (WDM) optical fiber systems, it is often necessary to switch the path of transmitted light. A number of different approaches have been utilized. Switching has been effected by mechanical movement of optical fibers (see P. G. Hale et al., Electronic Lett., vol. 12, p. 388,1976, and Y. Ohmori et al., Appl. Optics, vol. 17, p. 3531, 1978). Switching can also be based Faraday rotation (see M. Shirasaki et al., Appl. Optics, Vol. 23, p. 3271, 1984).
Switching based on reflecting mirrors is particularly attractive for communication systems but has not yet achieved its potential. (see Tanaka et a/. U.S. Pat. No. 4,498,730, L. Y. Lin et al, IEEE Photonics Technology Lett., Vol. 10, p. 525,1998, R. A. Miller et al., Optical Eng., Vol. 36, p. 1399, 1997, and by J. W. Judy et al., Sensors and Actuators, Vol. A53, p. 392, 1996). Switches using reflecting mirrors are convenient in that they use free-space light transmission and are potentially expandable to a large-scale optical crossconnect system. They typically employ electrostatic, piezoelectric or electromagnetic actuation means to move or rotate the mirrors and alter the light paths. The problem with these devices is that they either require the use of continuous application of power to maintain the shifted mirror position or their position is unstable. For example electrostatic devices are prone to charge build up and leakage, and hence are very sensitive to environment. Accordingly there is a need for latchable optical switches in which power is not required once the light path is shifted to a desired direction and for which the latched position is stably maintained.